package algocasts;

public class P82_mergeTrees {
    class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;
    }

    // Time: O(n)  Space: O(n)
    public TreeNode mergeTrees(TreeNode t1, TreeNode t2) {
        if (t1 == null && t2 == null) return null;
        if (t1 != null && t2 == null) return t1;
        if (t1 == null && t2 != null) return t2;
        t1.val += t2.val;
        t1.left = mergeTrees(t1.left, t2.left);
        t1.right = mergeTrees(t1.right, t2.right);
        return t1;
    }
}
